Autonomic dysreflexia and Some Causes

    Autonomic dysreflexia, or hyperreflexia, is a massive uncompensated cardiovascular reaction of the sympathetic division of the autonomic nervous system to visceral stimulation that occurs in clients with spinal cord lesions above T6. The autonomic nervous system is the part of the nervous system that is concerned with control of involuntary bodily functions. It regulates the function of glands, especially the salivary, gastric, and sweat glands, and the adrenal medulla; smooth muscle tissue; and the heart. The autonomic nervous system may act on these tissues to reduce or slow activity or to initiate their function. It is divided into the sympathetic and parasympathetic divisions. Autonomic dysreflexia concerns the sympathetic division.

 Stimulating sympathetic fibers usually produces vasoconstriction in the part supplied, general rise in blood pressure, erection of body hair, goose-flesh, pupillary dilation, secretion of small quantities of thick saliva, depression of gastrointestinal activity, and acceleration of the heart. In general these activities occur under emergencies such as fright and are associated with the expenditure of energy as a response to the need to either flee, fight, or to be frightened. They are mediated through the release of a transmitter agent, norepinephrine.

 The condition of autonomic dysreflexia can be a life-threatening situation that requires immediate resolution.

 The most common precipitating cause is a distended bladder or rectum, although any sensory stimulation may cause dysreflexia. Contraction of the bladder or rectum, stimulation of the skin, or stimulation of the pain receptors may also cause autonomic dysreflexia.

 Manifestations include hypertension (up to 300 mm/Hg systolic), blurred vision, throbbing headache, marked diaphoresis above the level of the lesion, bradycardia (30 to 40 beats per minute), piloerection (erection of body hair) as a result of pilomotor spasm, nasal congestion, and nausea.

 The pathology of autonomic dysreflexia involves the stimulation of sensory receptors below the level of the cord lesion. The intact autonomic system reacts with a reflex arteriolar spasm that increases blood pressure. Baroreceptors in cerebral vessels, the carotid sinus, and the aorta sense the hypertension and stimulate the parasympathetic system. The heart rate is decreased, but the visceral and peripheral vessels do not dilate because efferent impulses cannot pass through the cord lesion.

 Interventions include elevation of the head of the bed 45 degrees, and assessment to determine the cause. Immediate catheterization to relieve the distention may be necessary. Skin stimuli such as tight clothes and shoes should be removed. If hospitalized, and symptoms persist, Regitine or Apresoline may be given.

 Clients and families need to be taught the causes and symptoms of autonomic dysreflexia. They need to understand the life-threatening nature of this dysfunction and know how to relieve the cause.
  The Paralyzed Veterans of America offer a consumer booklet titled, "Autonomic Dysreflexia: What You Should Know." It is available for free by calling 1-888-860-7244. The booklet also contains a wallet card that can alert medical professionals to this condition.